<html>

<?php

// read the post from PayPal system and add 'cmd'
    $req = 'cmd=_notify-validate';
    foreach ($_POST as $key => $value) {
        $value = urlencode(stripslashes($value));
        $req .= "&$key=$value";
    }
    // post back to PayPal system to validate
    $header = "POST /cgi-bin/webscr HTTP/1.0\r\n";
    // If testing on Sandbox use: 
     $header .= "Host: www.sandbox.paypal.com:443\r\n";
    //$header .= "Host: ipnpb.paypal.com:443\r\n";
    $header .= "Content-Type: application/x-www-form-urlencoded\r\n";
    $header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
if (strpos('ssl://www.sandbox.paypal.com', 'sandbox') !== FALSE && function_exists('openssl_open')) {
    $fp = fsockopen('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);
  }
  else {
    // The old "normal" way of validating an IPN.
    $fp = fsockopen('ssl://www.sandbox.paypal.com', 80, $errno, $errstr, 30);
}
    // If testing on Sandbox use:
    //$fp = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);
    //$fp = fsockopen ('ssl://ipnpb.paypal.com', 443, $errno, $errstr, 30);
    // assign posted variables to local variables
    $item_name          = $_POST['item_name'];
    $item_number        = $_POST['item_number'];
    $payment_status     = $_POST['payment_status'];
    $payment_amount     = $_POST['mc_gross'];
    $payment_currency   = $_POST['mc_currency'];
    $txn_id             = $_POST['txn_id'];
    $receiver_email     = $_POST['receiver_email'];
    $payer_email        = $_POST['payer_email'];
    if (!$fp) {
     // HTTP ERROR
    } else {
        fputs ($fp, $header . $req);
        while (!feof($fp)) {
            $res = fgets ($fp, 1024);
            if (strcmp ($res, "VERIFIED") == 0) {
                // check the payment_status is Completed
                // check that txn_id has not been previously processed
                // check that receiver_email is your Primary PayPal email
                // check that payment_amount/payment_currency are correct
                // process payment
                $mail_From = "From: paypal@datyy.de";
                $mail_To = "milojevic.sasa@gmail.com";
                $mail_Subject = "VERIFIED IPN";
                $mail_Body = $req;
                foreach ($_POST as $key => $value){
                    $emailtext .= $key . " = " .$value ."\n\n";
                }
                mail($mail_To, $mail_Subject, $emailtext . "\n\n" . $mail_Body, $mail_From);
            }
            else if (strcmp ($res, "INVALID") == 0) {
                // log for manual investigation
                $mail_From = "From: paypal@datyy.de";
                $mail_To = "milojevic.sasa@gmail.com";
                $mail_Subject = "INVALID IPN";
                $mail_Body = $req;
                foreach ($_POST as $key => $value){
                    $emailtext .= $key . " = " .$value ."\n\n";
                }
                mail($mail_To, $mail_Subject, $emailtext . "\n\n" . $mail_Body, $mail_From);
            }
        }   // while end
     fclose ($fp);
    }

?>
</html>